Ashwini Sharma pointed out that my previous tweak to [!abc] groups still didn't get the error reporting right (test case "touch -d 12 -r f2 f1"). This says "no 'r' with 'd'" for that, and still shouldn't be able to fall off the end of the list (segfault) because an option can't conflict with itself (that's what the ~(1<<i) on lib/args.c line 317 is for).

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/args.c b/lib/args.c
index e4b774b4..67c7788a 100644
--- a/lib/args.c
+++ b/lib/args.c
@@ -132,8 +132,10 @@ static int gotflag(struct getoptflagstate *gof, struct opts *opt)
     struct opts *bad;
     unsigned i = 1;
 
-    for (bad=gof->opts; opt == bad || !(gof->excludes & i); bad = bad->next)
-      i<<=1;
+    for (bad=gof->opts, i=1; ;bad = bad->next, i<<=1) {
+      if (opt == bad || !(i & toys.optflags)) continue;
+      if (toys.optflags & bad->dex[2]) break;
+    }
     error_exit("No '%c' with '%c'", opt->c, bad->c);
   }